The present invention refers to a plastic product and especially to a security seal with individualized identification and to an injection mold for manufacturing the product.
The product to which this invention refers is of the plastic injection molded type having an identification surface to which an individualized marking is applied, such as a number, bar code or the like.
One of the essential requirements for a security seal to have a high degree of security is that it is individualized so as to prevent its substitution by another identical seal. One of the safest ways of effecting such individualization is by means of numbering in high relief during injection of the plastic from which the seal is made. This solution, however, is relatively costly in view of the resultant complexity of the mold and of the maintenance thereof.
A less costly technique is to adhere a strip of paper to the identification surface, on which a number or other marking which serves to distinguish the seal from otherwise identical seals is printed. Mere adhesion, however, does not provide a high degree of security in view of the possibility of removing the printed strip from a tampered seals and later applying it to another seal. This process may be made more difficult and there are various ways of doing this, but the danger of the strip being removed and re-utilized is always present.
Another manner of applying a personalized strip of paper is to apply it at the time of injecting the plastic so that the strip becomes integral with the seal at the time of manufacture. Although this technique does have excellent results and is considerably superior to simple gluing, all papers have a laminated structure and this permits a violator to delaminate the strip, removing the upper layer or layers with the number printed thereon and leaving only the lowermost layer on the tampered seal. The removed strip can then be glued onto a new seal, making it difficult to identify the violation.
A first object of the present invention is to individualize a plastic product, such as a security seal of the type mentioned above, using a printed strip of paper fixed to an identification surface, at low cost and without compromising the desired high degree of security provided.
Another object of the invention is to provide an injection mold for manufacturing the product.
According to a first aspect of the present invention, a product made from injected plastic and having an identification surface to which a strip of paper printed with an individualized identification is fixed, is characterized in that at least part of the identification surface has at least one protuberance covered by the strip of paper, to define at least one abrupt change in the plane of part of the outer surface of the strip of paper.
A product having such a characteristic will not permit the removal of the complete outer face of the strip of paper without tearing. Consequently, if the part removed by a violator is glued to another similar product, it will always be incomplete or damaged, leaving clear vestiges of adulteration.
In the preferred embodiments of this invention, there are various protuberances on the identification surface, which may take the form of square or rectangular protuberances, small pins, small tooth-like formations or the like. The important feature is that the outer or exposed surface of the strip of paper has portions the plane of which changes abruptly along crease lines, edges or the like, such abrupt changes in direction of the surface of the paper adhered to the identification surface favoring the formation of tear regions in the eventuality of an attempt at removal.
According to a second aspect of the present invention, a product made from injected plastic and having an identification surface to which a strip of paper printed with an individualized identification is fixed, is characterized in that at least part of the outer surface of the strip of paper is covered by the injected plastic of the product.
As in the first aspect of the invention as mentioned above, such a characteristic will not permit the removal of the complete outer face of the strip of paper without tearing.
In a preferred embodiment of the second aspect of the invention, it has been found that a particularly practical manner of making the injected plastic pass to the outer surface of the strip of paper is by the partial perforation of the paper in the corresponding region.
The invention also relates to an injection mold for manufacturing a plastic product with individualized identification, which comprises first and second injection mold halves, the first mold half being formed with an injection cavity for forming part of the product to be personalized by solidifying the injected plastic with a printed strip of paper placed between the mold halves, and the second mold half closing the cavity in a closed configuration of the mold with the halves in mutual contact.
In the case of a mold for manufacturing a product in accordance with the first aspect of the invention, as mentioned above, small reentrances are formed in the second mold half so as to permit that, at the time of injection of the plastic in the closed configuration of the mold, the plastic under pressure in the injection cavity deforms small regions of the strip of paper, forcing them into the small reentrances.
Preferably, there are two series of the small reentrances in the second mold half, located at positions corresponding to two opposite sides of the injection cavity. Each small reentrance may have a constant rectangular cross section, parallel to the surface of the second mold half.
In the case of a mold for manufacturing a product in accordance with the second aspect of the invention, as mentioned above, the second mold half is shaped so as to permit, at the time of injection of the plastic in the closed configuration of the mold, the plastic at least partially covers the side of the strip of paper that is remote from the mold cavity.
In this case it is preferred that there are two roughened regions located at positions corresponding to two opposite sides of the injection cavity. Each of these roughened regions may extend completely along the respective side of the cavity, in the closed configuration of the mold. Furthermore, there can be four roughened regions located at positions, in the closed configuration of the mold, corresponding to the four corners of the cavity.